Posted by Charlie on April 25, 1999 at 18:09:00:
In Reply to: Re: cummings diesel in a older powerwagon? posted by Paul on April 25, 1999 at 14:55:56:
The naturally aspirated Nissan SD33 is a 3.3L indirect injected six, with about 80HP@4000 and 135-140 ft-lb torque@2200 - very anemic for a 6000 lb M37. The Mitsubishi 6DR5 is a totally different engine, it's 4.0L, again indirect injection, but 110HP@3700, 184 ft-lb@2000. If turbocharged, it would put out a very adequate 150HP and 250 ft-lb. Even in naturally aspirated form, it would propel a 4500 lb or even 6000 lb truck IF (VERY IMPORTANT) geared properly!!!! That means NOT with a wide ratio NP435, like it came with, but with a close ratio 5 or even 6 speed. An engine with this power to weight ratio requires a transmission with 35-40% splits ("ratio ratios" of 1.34-1.40), not 66-100% splits. RPMs must be kept up, in the case of the 6DR5, in the 2500-3500 range when accelerating or climbing hills. This failure to gear properly is the downfall of most installations of smaller diesels in full-sized American vehicles. Just stupidity, laziness or cheapness on the part of the mfgs. Of course these engines come with 5 and 6 and even 5X2 speeds when installed in Japanese made forward control 3/4-2 ton trucks. The Hercules does well in the M37 even with the wide ratio transmission only because it puts out a massive 268 ft-lb. It would do better with a 1.28:1 gear in there between 3rd and 4th, also a 0.80:1 overdrive.
Charlie